肌间多尺度时频耦合分析方法研究

Study on the Method of Intermuscular Multi-scale Time-frequency Coupling Analysis

目的探讨脑卒中患者表面肌电(sEMG)信号间的耦合特性差异,为运动功能康复评估提供新的指导方法。方法提出一种新的时频耦合(TFC)分析方法,从时频互信息、时频归一化互信息和时频条件互信息3个指标度量时频非线性耦合强度。首先在仿真数据上验证TFC的有效性,然后将噪声辅助的多元经验模态分解与TFC相结合,构建多尺度时频耦合(Ms-TFC)分析模型,并用于研究5名健康人和5名卒中患者上肢及物运动过程中三角肌前束(AD)、中束(MD)和后束(PD)的肌间耦合特性差异。结果卒中患者和健康人的AD、MD、PD在4个平均累积方差贡献率超过90%的本征模态函数(IMF)尺度分量上,肌间耦合强度低且接近,轻度运动功能障碍的卒中患者与健康人不具有显著性差异(P>0.05)。结论AD、MD和PD在不同尺度上可能是统计独立的,Ms-TFC能够定量描述肌间多尺度时频非线性耦合特征。

Objective To investigate the differences of coupling characteristics between surface electromyography(sEMG)signals in stroke patients,so as to provide new guidance for the rehabilitation assessment of upper limb motor function.Methods A new time-frequency coupling(TFC)analysis method was proposed and the time-frequency nonlinear coupling strength was measured by three indicators including the time-frequency mutual information,the time-frequency normalized mutual information and the time-frequency conditional mutual information.Firstly,the effectiveness of TFC was verified by the simulation data.Then,a multi-scale time-frequency coupling(Ms-TFC)analysis model was constructed by combining noise assisted multiple empirical mode decomposition with TFC.The model was applied to study the differences of intermuscular coupling characteristics of anterior deltoid(AD),medial deltoid(MD)and posterior deltoid(PD)of the deltoid muscles during upper limb reaching movement of 5healthy controls and 5stroke patients.Results Experimental results showed that the intermuscular coupling strength of AD,MD and PD in stroke patients and healthy controls was low and close on the four intrinsic mode function(IMF)scale components whose average cumulative variance contribution rate was more than 90%,and there was no significant difference between stroke patients with mild motor dysfunction and healthy controls(P>0.05).Conclusion AD,MD and PD may be statistically independent at different scale components.Ms-TFC can quantitatively describe multiscale time-frequency nonlinear coupling characteristics of muscles,which can provide a new guiding method for rehabilitation evaluation of motor function.